Debt - Additional Information (Detail) | Jun. 26, 2017USD ($)Acquisitionshares | Jun. 20, 2017USD ($)Day$ / sharesshares | Sep. 30, 2017USD ($)shares | Sep. 30, 2016USD ($) | Jul. 31, 2017USD ($) | Jun. 30, 2017shares | Jun. 24, 2017USD ($) |
Debt Instrument [Line Items] | | | | | | | |
Number of shares of common stock repurchase | shares | | | 27,639,876 | | | 25,941,476 | |
Number of business acquisitions provided with additional cash resources | Acquisition | 2 | | | | | | |
Remaining debt issuance costs expensed | | | $ 1,300,000 | $ 300,000 | | | |
Debt issuance cost | | | $ 1,100,000 | | | | |
Percentage of voting capital stock | | | 65.00% | | | | |
Revolving Credit Facility [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Outstanding principal amount | | | | | | | $ 100,000,000 |
0.50% Convertible Senior Notes due 2022 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument aggregate principal amount | | | $ 525,000,000 | | | | |
Credit Agreement [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Outstanding principal amount | | | | | | | 220,000,000 |
Credit Agreement [Member] | Revolving Credit Facility [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Line of credit facility amount | | | | | $ 250,000,000 | | 450,000,000 |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt amortization period | | | 60 months | | | | |
Outstanding principal amount | | | $ 0 | | | | |
Line of credit facility amount | | | 200,000,000 | | | | |
Line of credit facility allowable requests for additional borrowing | | | $ 100,000,000 | | | | |
Maturity period | | | Sep. 27, 2022 | | | | |
Repayment date, description | | | The revolving credit facility is required to be repaid in full on the earlier of (i) September 27, 2022 and (ii) the date 91 days prior to the Maturity Date of Notes if the Notes have not been refinanced in full by such date. | | | | |
Debt issuance cost | | | $ 2,300,000 | | | | |
Description of base rate | | | The revolving credit facility bears interest at our election of a Base Rate plus an Applicable Margin or LIBOR plus an Applicable Margin. Swingline loans bear interest at a Base Rate plus an Applicable Margin. The Base Rate is a floating rate that is the greater of the Prime Rate, the Federal Funds Rate plus 50 basis points, or LIBOR plus 100 basis points. The Applicable Margin is based on a sliding scale which ranges from 0.25 to 100 basis points for Base Rate loans and 100 basis points to 175 basis points for LIBOR loans. | | | | |
Covenant description | | | Under the Agreement, there are various restrictive covenants, including three financial covenants which limit the consolidated total leverage ratio, or leverage ratio, the consolidated interest coverage ratio, or interest coverage ratio, a restriction which places a limit on the amount of capital expenditures that may be made in any fiscal year, a restriction that permits up to $50 million per fiscal quarter of accounts receivable financings, and sets the Specified Leverage Ratio. The leverage ratio is the ratio of debt as of the measurement date to earnings before interest, taxes, depreciation and amortization, or EBITDA, for the four consecutive quarters ending with the quarter of measurement. The current leverage ratio shall not exceed 3.50 to 1.00 provided that for the four fiscal quarters ending after the date of a material acquisition, such maximum leverage ratio shall be adjusted to 3.75 to 1.00, and thereafter, shall not be more than 3.50 to 1.00. The interest coverage ratio is EBITDA to interest expense for the four consecutive quarters ending with the quarter of measurement. The interest coverage ratio must not be less than 3.50 to 1.0 during the term of the Agreement. The Specified Leverage Ratio is the ratio used in determining, among other things, whether we are permitted to make dividends and/or prepay certain indebtedness, at a fixed ratio of 3.00 to 1.00. As of the end of the quarter, we were in compliance with the restrictive covenants. | | | | |
Maximum accounts receivable financings per quarter | | | $ 50,000,000 | | | | |
Maximum leverage ratio permitted | | | 3.50% | | | | |
Minimum interest coverage ratio | | | 3.50% | | | | |
Fixed coverage ratio | | | 3.00% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | For The First Four Fiscal Quarters Ending After Date of Material Acquisition [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Maximum leverage ratio permitted | | | 3.75% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Thereafter [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Maximum leverage ratio permitted | | | 3.50% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Federal Funds Rates [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 0.50% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | LIBOR [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 1.00% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Commitment fee percentage of unused portion | | | 0.175% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 1.00% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member] | Base Rate [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 0.0025% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Commitment fee percentage of unused portion | | | 0.25% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 1.75% | | | | |
Amendment and Restatement Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member] | Base Rate [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Basis spread on variable rate | | | 1.00% | | | | |
Amendment and Restatement Agreement [Member] | Letter of Credit [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Line of credit facility amount | | | $ 20,000,000 | | | | |
Amendment and Restatement Agreement [Member] | Bridge Loan [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Line of credit facility amount | | | $ 20,000,000 | | | | |
Purchase Agreement [Member] | 0.50% Convertible Senior Notes due 2022 [Member] | Wells Fargo Securities, LLC [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument aggregate principal amount | | $ 500,000,000 | | | | | |
Debt instrument additional aggregate principal amount | | $ 25,000,000 | | | | | |
Option to purchase additional principal amount of notes granted to initial purchasers, period | | 30 days | | | | | |
Net proceeds from issuance of convertiable debt | $ 514,500,000 | | | | | | |
Number of shares of common stock repurchase | shares | 1,698,400 | | | | | | |
Interest rates on borrowings | | 0.50% | | | | | |
Debt instrument maturity date | | | Jun. 15, 2022 | | | | |
Conversion of notes in multiples of principal amounts | | $ 1,000 | | | | | |
Convertible number of shares, principal amount of notes | shares | | 13.6947 | | | | | |
Initial conversion price per share of common stock | $ / shares | | $ 73.02 | | | | | |
Note repurchase price, percentage of principal amount of notes | | 100.00% | | | | | |
Sale price of common stock, minimum threshold percentage | | 130.00% | | | | | |
Sale of common stock, threshold trading days | Day | | 20 | | | | | |
Sale of common stock, threshold consecutive trading days | Day | | 30 | | | | | |
Equity component of the principal amount of the convertible debt | | $ 82,100,000 | | | | | |
Nonconvertible debt borrowing rate | | 4.39% | | | | | |
Debt instrument term | | 5 years | | | | | |
Debt issuance costs | | $ 11,100,000 | | | | | |
Initial purchaser’s discount | | 10,500,000 | | | | | |
Legal, accounting, and printing costs | | 579,000 | | | | | |
Convertible debt issuance costs pro rata to equity components | | 1,900,000 | | | | | |
Convertible debt issuance costs pro rata to debt components | | $ 9,200,000 | | | | | |
Debt amortization period | | 5 years | | | | | |
Unamortized amounts of debt issuance costs | | | $ 8,700,000 | | | | |
Unamortized amounts of debt discount | | | 78,200,000 | | | | |
Term Loan Arrangement [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Outstanding principal amount | | | | | | | $ 120,000,000 |
Term Loan Arrangement [Member] | Amendment and Restatement Agreement [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Remaining debt issuance costs expensed | | | $ 1,000,000 | | | | |